The invention relates to a canister purge valve, and more particularly to a canister purge valve providing an increase in a flow rate through the valve for an increase in power level to a coil and/or an increase in duty cycle.
It is known to use an armature in a canister purge valve to permit and prohibit flow through the housing of a canister purge valve. A known canister purge valve has a spring disposed between a stator and the armature. The spring biases the armature towards a seat to prohibit flow through the valve housing. Energization of an electromagnetic coil magnetically attracts the armature in a direction that is toward the stator and away from the seat (i.e., in a direction that opposes the bias of the spring), thereby permitting flow through the housing of the valve.
In the known valve, an air gap exists between the stator and the armature. It is believed that the interaction among the air gap, spring, and coil that actuates the armature and the stator can cause a fluid flow rate through the valve to drop for an increase in duty cycle and/or increase in power to the coil, and can cause a fluid flow rate through the valve to increase non-linearly for an increase in duty cycle and/or increase in power to the coil. Thus, it is believed to be desirable to provide a valve that increases a flow rate through the valve for an increase in power level to a coil.
The invention provides a canister purge valve that increases flow through the valve for an increase in power level. The canister purge valve includes a housing that defines a volume and has an inlet and an outlet in fluid communication with the volume. A coil is disposed in the volume proximate the outlet. A stator is disposed in the volume proximate the outlet, the stator having a first surface. An armature is disposed in the coil, the armature having a second surface proximate the first surface of the stator and defining a gap therebetween. The armature is movable to an open position permitting fluid flow through the volume in response to an energization of the coil. A biasing member is disposed between the stator and the armature, the biasing member urging the armature to a closed position prohibiting fluid flow through the volume. An elastomeric contact member is disposed in the gap, the member maintaining continuous contact with the first and second surfaces during an entire movement of the armature between the open and closed positions.
The invention also provides a method of maintaining an increase in flow rate for an increase in duty cycle in a system having a housing defining a volume, the system having a coil, a stator, and an armature disposed in the volume. The method can be achieved by energizing the coil to attract the armature towards the stator, and maintaining continuous contacting between the armature and the stator with a compressible member during energization and deenergization of the coil.
The invention also provides a method of maintaining an increase in flow rate through a valve defining a void, the valve including a coil, a stator, and an armature disposed in the void. The method can be achieved by energizing the coil to attract the armature towards the stator and permit flow through the valve, and disposing a compressible member between the armature and the stator, the member deforming during movement of the armature and providing an increase in a flow rate through the valve.